Surface Probe NMR Measurement for Shallow Subsurface Analysis
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Solution Overview
Problem
Current geophysical NMR techniques face challenges in rapidly obtaining information about the properties of shallow or very shallow subsurface regions due to low signal-to-noise ratios and limited spatial resolution in Earth's Field Surface NMR (EF-SNMR) methods, while downhole logging NMR requires invasive borehole installation.
Innovation Solution
Development of surface-based NMR measurement technologies using a surface probe positioned above the Earth's surface, equipped with permanent magnets and induction coils to generate and detect NMR signals, allowing for non-invasive measurements of shallow or very shallow subsurface volumes with improved signal-to-noise ratios and spatial resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Earth's Field Surface NMR (EF-SNMR) is used to perform non-invasive measurements, then the need for borehole installation is eliminated, but the signal-to-noise ratio becomes very low
Solution Approach 1:
The patent changes the magnetic field strength parameter by introducing permanent magnets to generate a stronger static magnetic field (e.g., 0.1-10 Tesla) compared to Earth's natural field (0.00005 Tesla). This parameter change directly increases the NMR signal amplitude, which is proportional to the square of the magnetic field strength, thereby resolving the low signal-to-noise ratio problem while maintaining non-invasive surface measurements
Solution Approach 2:
The patent employs a composite measurement system combining permanent magnets (for strong static field), RF coils (for excitation and detection), and surface probe structures. This composite approach integrates multiple functional components to achieve both non-invasive operation and high signal-to-noise ratio simultaneously
2Ease of operation
If EF-SNMR uses large coils over large volumes to compensate for weak signal, then non-invasive measurement is maintained, but spatial resolution deteriorates
Solution Approach 1:
The patent applies local quality by concentrating the magnetic field and NMR excitation in a localized subsurface volume directly beneath the surface probe. The permanent magnets create a focused measurement zone, allowing spatially resolved NMR measurements of shallow subsurface features without requiring large coils, thereby achieving both non-invasive operation and improved spatial resolution
Solution Approach 2:
The patent transitions from the conventional horizontal coil configuration to a vertical surface probe configuration with magnets arranged to generate a downward-directed magnetic field. This dimensional change in field orientation enables focused subsurface measurement volumes and improves spatial resolution while maintaining non-invasive surface-based operation
3Measurement precision
If downhole logging NMR is used to obtain high signal-to-noise measurements, then measurement precision is improved, but the requirement for borehole installation increases device complexity and invasiveness
Solution Approach 1:
The patent extracts the permanent magnets and NMR measurement components from the downhole environment and places them on the surface. By taking out the magnetic field generation and detection system from the borehole and positioning it on the surface, the patent eliminates the need for invasive borehole installation while maintaining the capability to generate strong magnetic fields and detect NMR signals from the subsurface
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient and non-invasive NMR measurements of shallow subsurface properties with enhanced spatial resolution and signal quality, facilitating rapid data acquisition without the need for borehole installation.
Implementation Method 1
The logging apparatus contains permanent magnets that create a static magnetic field for the NMR measurement
Implementation Method 2
one or more coils or antenna used to excite an NMR signal from fluids in the Earth formation
Implementation Method 3
one or more coils or antenna deployed on Earth's surface to excite and measure the NMR response of subsurface fluids
Data Source
AI summary
Technologies applicable to surface-based NMR measurement are disclosed. A surface probe is positionable at or above a surface of the Earth and adapted to make NMR measurements of shallow or very shallow subsurface volumes. NMR spectrometer components connected to the surface probe are configured to control electromagnetic pulses produced by the surface probe and to record resulting detected NMR signals from the subsurface volume.